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排序方式: 共有275条查询结果,搜索用时 31 毫秒
61.
62.
Marcelo Motta Ian Kinloch Anna Moisala Venugoplan Premnath Martin Pick Alan Windle 《Physica E: Low-dimensional Systems and Nanostructures》2007,37(1-2):40
We have recently introduced a method for the continuous spinning of carbon nanotube fibres and films directly from the gas phase of a chemical vapour deposition furnace [Y. Li, et al., Science 304 (2004) 276]. In this work the effect of the process parameters on the ability to spin continuously is studied, with particular focus on the carrier gas and feedstock flow rates. Catalyst dilution by high carrier gas flow rates led to smaller diameter nanotubes but these conditions are found the hardest to spin. 相似文献
63.
64.
Recently, the present authors have suggested that some of the basic features of the unstable W(001)-(1×1) surface can be explained by the competition between the direct attractive and indirect repulsive interactions present at the surface. To understand this mechanism in more detail, number of surface structures (steps in the (0,1) and (1,1) direction, vacancy, adatoms etc.) have been investigated within a simple LCAO recursion scheme. The direct interactions (two-body term) and the indirect ones (three-body terms) are approximately additive for surface atoms and adatoms having four nearest neighbours. The unreconstructed (1×1) surface is under compressive (repulsive) stress and we suggest that, for example, steps should expand near their edges. 相似文献
65.
The comparison of thermal stabilities of different organoclay intercalation complexes is presented in this work. Montmorillonite/monomer and montmorillonite/polymer intercalation complexes with similar basal spacings show a pronounced difference in changes of d
001 values after 30 min heating. The hydrophilic and/or organophilic surface modification of the starting montmorillonite is an important factor affecting the intercalated amount of organic material and thus the expansion of the sheet silicate structure.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
66.
The kinetics of aminolysis of 1-thio-β-D-glucopyranosyl esters of N-protected alanines (1) in dichloromethane, at 26°, by ethyl glycinate, under pseudo-first-order conditions follows the relationship k-obsd = k2[H-Gly-OEt]. Significant differences were observed in the rates of dipeptide forming aminolysis for 1-thiolesters 1a-1f, depending on N-acyl substituents and the configuration of alanine. 相似文献
67.
Dr. Ilya Popov Dr. Teng‐Hao Chen Dr. Sergey Belyakov Prof. Olafs Daugulis Prof. Steven E. Wheeler Prof. Ognjen Š. Miljanić 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(7):2750-2754
We report structural characterization of a new member of m‐phenylene ethynylene ring family. This shape‐persistent macrocycle also co‐crystallizes with hexafluoro‐, 1,2,4,5‐tetrafluoro‐, 1,3,5‐trifluoro, and 1,4‐difluorobenzene. The four complexes are almost isostructural, and all show the fluoroarene included into the central cavity of the macrocycle. Characterized by multiple short C?H???F?C contacts, these inclusion complexes further dimerize in the solid state into a 2+2 assembly, in which the two macrocycles embrace each other by their large hydrophobic groups that are rotated by 60° relative to one another. 相似文献
68.
The vertical distribution of85Sr and137Cs in undisturbed single-contaminated agricultural soils have been studied during their irrigation with wet atmospheric precipitation
in dependence on time under laboratory conditions for about one year. The soil samples were collected from several localities
in the environment of nuclear power plants at Dukovany and Jaslovské Bohunice using a special auger. The samples were placed
into polyethylene columns of 9 cm in diameter and 20 cm in height. The activity of radionuclides in soil profiles after their
separation into single layers were counted by Ge(Li) semiconductor gamma-spectrometry. Based on the exponential depth distribution
of radionuclides, the values of their migration parameters as relaxation depth, migration rate and retardation factor were
calculated. The influence of the permanent grass cover and of the applied zeolite on the migration parameters of these radionuclides
was also investigated.
Presented at the Conference “Nukleonika '98”, Prague, Czech Republic, 9–10 September 1998, dedicated to late Professor František
Běhounek in honour of his 100th birthday. 相似文献
69.
70.
Georg Pick 《Monatshefte für Mathematik》1936,43(1):29-43
Ohne Zusammenfassung 相似文献